Interference measurements for roughness of silicon mirrors with Twyman Interferometer

Supposed the random distribution of height deviation can be represented as Gaussian distribution, the relationship between intensity contrast C of interference hinges, determined at Twyman Interferometer, and the roughness sigma of minor's surface is deduced. Roughness measurements of four silicon mirrors have performed with Twyman Interferometer. The results of measurements is agree with the data, measured by 6JA profiler in tendency. This method is a full-field, noncontacting interference measurement so that it can be developed as a inspection on line. Then, the surface profile analysis can also be perform from interference fringes. Therefore this method provide a controlling way in polish process.